Coincidence range finder



June 1946- B. E. LUBOSHEZ ZAQLW COINCIDENGE RANGE FINDER Filed July 18, 194i 2 Sheets-Sheet 1 INVENTOR BY W/ ATTORNEY Benjamin E .Luboshez 0. I n 2.4 I I 5 9 a 0 m w 1% m 0 u 3 4 ma June 4, 194 6.

B. E. LUBOSHEZ COINCIDENGE .RANGE FINDER Filed July 18, 1941 2 ShetS-Sh96t 2 a aaaxcaaar' &

Benjamin ELuboshez INVENTOR By Wzflww A TTORXE Y Patented June 4, 1946 UNITED STATES PATENT OFFICE COINCIDENCE RANGE FINDER Benjamin E. Luboshez, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application July 18, 1941, Serial No. 402,986

6 Claims. 1

.This invention relates to range finders and particularly to a modification of the moving viewpoint type of range finder described in my copending application, Serial No, 402,982, filed concurrently herewith. The present invention is also useful with the forms of moving viewpoint range finders described in my other applications also filed concurrently herewith, Serial Nos. 402,- 983, 402.984 and 402,985.

Thepresent invention is a combination of a moving viewpoint range finder and a coincident type range finder. One embodiment of it is a combination of both of these types of range finders and a stereo range finder.

It, is an object of the invention to provide a method and means for rapidl and accurately finding the range of an object, It is a particular object of the invention to provide an instrument whichcan be used for finding the range of objects which do not hav sharp lines as required for ordinary coincident type range finders. On the other hand, it is an object of the invention to provide a method of range finding in which approximate adjustment can be rapidly reached and the final critical adjustment be made accurately.

According to the invention a moving viewpoint range finder is provided with two viewpoints givingsuperimposed images in the focus plane of the eyepiece. The light deviating means used for control of theimage motion as described in my copending applications is also arranged so that even when the viewpoints are stationary this light deviating meanscan be used for bringing the two images into coincidence. The images are first brought into coincidence to give the approximate range and then the viewpoint of at least one of the images is shifted along a repetitive path, for example, rotated. If the images were in perfect coincidence, there would be no apparent shift of the images. However, if perfect coincidence is not obtained, th residual image-motion can be eliminated by adjusting the light deviating means more accurately, Thus this method provides rapid operation into approximately correct adjustment and then accurate operation to get the final critical'adjustment. i

Anothercbject of this invention is to provide reference frames against which the movement of the image of the target can be observed, such. relative movementsbeing independent of accidental movement or vibration, of the whole instrument.

Theinvention will be fullyunderstood from the following description when read in connection with the accompanying drawings in which:

, 2 Fig. 1 illustrates the principle of moving viewpoint range finders.

Fig. 1A shows the field view as seen through the instrument.

Fig. 2 shows one embodiment of the invention.

Fig. -3 shows a different embodiment of the invention. I

Fig. 4 shows still a third embodiment of the invention.

Fig. 5 shows a specific embodiment of the invention wherein stereo range finding is also combined with the coincident type and moving viewpoint type combination.

In Fig, l a range finder having a housing 20 is provided with an objective 2| for forming in its focu plane an image of the object whose range is to be found. The eye 24 of an observer views this image through aneyepiece 22. On the front of the housing 20 is mounted a rotating arm 25 having reflecting surfaces 26 and 2'! oriented to receive light from the object and to transmit it to the objective 2|. Considering only objects on the rotation axis 3| of the system, which coincides partly. with the optic axis of the objective 2|, thoseat infinity submit rays 28 and 29 to form an image at the point 30 on this optic axis. Those at a nearer range submit rays 32 and 33 to form an image 34to one side of this optic axis. As the rotating arm 25 is rotated, the image 34 moves circularly about the optic axis 3L All other points on the object, at this nearer range. 1. e., those points not on the rotation axis, also move with a circular motion, but the image as a whole remains inverted in the image plane 23. Proper adjustmentof either the mirror 26 or the mirror 21 or adjustment of variable wedge or other light deviating means can be made to bring the image 34 down to the axis 3! at which. time there willbe no motion of the image 34 when the rotating arm 25 is rotated.

In .Fig. 1A is shown the field of view when ranging an object, for example, a flag. In this field is seen a fixed image shown b broken lines 31. such for example that formed by light through the aperture 49 of Fig. 2 described below. When the instrument is operated, an image 36 rotates about this fixed-image 31, without changing its orientation, until the instrument is adjusted to eliminate this rotary motion.

In 2 the eyepiece 40 behind an erecting prisrn dl views the image formed b an objective 42 mounted for rotation within a rotating tube 43 carrying a rotor 44. The main viewpoint of the objective 42 is provided by a reflector 45 and a reflector 46 formed in a single prism. A central aperture 41 in the reflector 46 is arranged by means of a wedge section of a cylinder 48 cemented thereto, to View the object directly through an aperture 49 in the rotor 44. Light reflected by the reflectors 45 and 46 on passing through the objective 42 are deviated by an adjustable prism 50, whereas light through the central aperture 4'! passes directl through an aperture in this prism 50. In practice the objective 42 and the prism 50 must both be as close as possible to the reflecting surface 46 or some additional means must be provided for preventing the reflected light passing through the aperture 5| and the axial light passing through the prism 50. The prism 50 is adjusted axially in this embodiment and is carried by asleeve 52 sliding in the rotating tube 43; this sleeve 52 is fastened by a pin 53 through a slot 54 in the tube 43 to a collar 56 which rotates with the tube 4.3. The collar 56 and sleeve 52 are adjusted against the pressure of a spring 55 by a ball race '51 engaged by a control member 58 which is screwed onto the frame 6| of the instrument by screw threads 59. The control member 58 carlies a scale 60 for indicating the adjustment in terms of the range of the object. For presetting the scale and compensating for the residual effect of the prism 50 at the infinity setting, an adjustable prism 62 is provided in front of the reflecting surface 45. l

In operation, the instrument is pointed at the object whose range is to be found and the prism 50 is adjusted axiall until the two images seen from the two viewpoints are approximately in coincidence. Then the rotor 44 is rotated which causes the reflected image torotate unless the prism 50 is in perfect adjustment. If there is any motion apparent in the images as seen, the prism 50 is further adjusted to eliminate this motion and the range read on the scale 60.

An alternative arrangement is shown in Fig. 3'

wherein an additional'prism I6 is mounted in front of the central aperture' l'l and has reflecting surfaces II and I2, the latter being behind a window I3 diametrically opposite the one transmitting light to the reflector 45. In this embodiment the adjustable prism I4, instead of having a central aperture, has its centralportion 15 also arranged as a prism with the direction of deviation reversed. The operation of this arrangement is the same as for Fig. 2. It is more sensitive in that the base determined by the distance between the .viewpoints is greater in Fig. 3 than in Fig. 2, but Fig. 2 is a much simpler arrangement.

In Fig. 4 the eyepiece 80 views the image formed by an objective 8| rigidly held in this case by a tube 82. Light is received through two viewpoints 86 and 81, the latter viewpoint sub free to rotate on the rotating tube butwhich rotates synchronously with it except when the wedges 88 are being adjusted. The rotating tube 4 95 carries a spur gear 96 and a similar spur gear 91 is mounted on therotor.

This latter gear 91 is driven by gears 98, 99, and hand wheel I00. It also engages an idler 05 which is in mesh with a spur gear I06 forming part of a differential with a second spur gear I0! engaging the gear 96. These gears I06 and I0! form a differential gear and rotate in opposite directions with the same speed when the gears 96 and 91 rotate synchronously. The gears I06 and I01 by means of crown gears I08 and I69 engage pinions IIO carried in ring gear III to form the differential. As long as the ring gear III remains stationary, the necessary equal and opposite rotation of the gears I06 and I0! is assured. However, this ring gear III is meshed,

with the crown gear II2 carried on a drum H3 and as said drum H3 is rotated, the gear I II is' The separation of the eyepieces 80 and H5 is preferably made adjustable to accommodate observers with different interocular separations.

Alteratively the drum 'I I3 may' be driven automatically by the rotation-of the rotor. To do this a knob and shaft I29 are'moved so that the pinion I on the end thereof engages a spur gear I26 attached to a gear I21 which meshes with a large crown gear I28 carried by the drum.

H3. Key and key Way'coupling I between the shaft and the knob I29 and the gear I06 causes the shaft to rotate when the gear I06 is rotated and this motion is transmitted to the gears I25 and I26when the latter are in mesh.

The drum II 3 rotates quite slowly, relatively to the rotation of the rotor. I

As before, the operation consists in first setting the wedges so that there is approximate coincidence between the images seen through the viewpoints 86 and 8"! and then rotating the rotor by the hand wheel I00 to provide image shift if the adjustment is not perfect. Any shift thus noted is then eliminated and the reading taken on the scale II4 through the eyepiece II5 Fig. 5 shows schematically how the invention may be further combined withthe stereo type of range finder. Suitable eyepieces I40 mounted in periscopes MI are positioned 'at interocular separation behind the housings I42 of the two systems. In each system a rotating member I43 is supported in proper bearing and the two ro- ,tating members I43 are geared through gears I44 to rot-ate together. The actual gears I 44 are not shown in detail since they may be either an even number or odd number of gears to provide respectively rotation in opposite directions or r0- tation in the same direction. Specific arrangements thereof are described in my copending application, Serial No. 402,984, mentioned above. Both rotors are driven by a friction drive engaging one of them and operated by motor I45, 'In each system an objective I 50 forms an image of the object whose range is to befound in a focus plane of the eyepieces I40. In this horizontal cross section, only the axial reflectors I52 of'the rotor are shown since the rim reflectors are above the plane of'the drawings. The axial portion I53 of each reflector I52 is arranged to view the object directly through axial apertures I54 in the rotor and housing. Behind the objective is positioned an adjustable wedge l5! having a central aperture I55. The adjustment of the wedges is provided by rings III!) which may be coupled or may be operated independently, the details of this feature not being shown, since they are described in my copending applications mentioned above and may be of any of the suitable forms shown.

Thus each of the stereo pair of optical systems involves the combination of moving viewpoint and coincidence adjustment and may be used to get an approximate setting by bringing superimposed images into coincidence and to get an accurate setting by noting the adjustment for complete elimination of image motion when the rotors are rotated. According to this specific embodiment of the invention, an additional feature is provided consisting of stereoscopic graticules lfiI in the focus planes of the eyepieces I40. These stereo gratioules may be used in various ways.

When the two rotors I43 are geared as by an odd number of gears in the gear system IM, to rotate in the same direction and in phase with each other, the distance between the two rim viewpoints of the systems remains constant and the whole instrument can at any time be used for stereo range finding. When the object Whose range is to be found does not contain any suitable sharp line, it is quite diilicult to use a coincident type range finder and the stereo feature .with the graticules when the rotors are stopped in some fixed position such as that shown in Fig. 5, in which the rim reflectors are separated by the same distance as the central viewpoints, or when they are at maximum separation, the graticules of course being ruled accordingly.

When the rotors are in motion the stereoscopic graticules form a fixed reference frame in depth against which the image instrument is observed.

Still another arrangement is possible when means are provided for distinguishing the axial viewpoints from the rim viewpoints. Such means ma consist of filters over one or other set of viewpoints or a shutter for cutting oil the rim viewpoints. In this arrangement, the stereo graticules can be used for taking stereo reading from the images formed by the axial viewpoints only.

This triple combination of moving viewpoint type, coincident type and stereo type range finders provides a system capable of extremely'rapid and accurate range finding.

Having thus described various arrangements of my invention, I wish to point out that it is not limited to these structures but is of the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

1. The method of range finding an object from two spaced viewpoint defining means which comprises forming by an optical system and in a single image plane, images of the object from the two viewpoints, adjusting a light deviating means to bring the images into approximate coincidence, rotating at least one of the viewpoint defining means and the light deviating means about the optic axis of the image plane with respect to the system without rotating the images, adjusting the light deviating means to eliminate relative movement of the two images and'noting the adjustment. j

A combination coincident type and moving viewpoint range finder comprising a rotor having at least two entrance windows, an eyepiece whose focus plane is in optical alignment with the rotation axis oi the rotor, means for receivin light through the two Windows and for forming in said focus plane superposed images of the object Whose range is to be found, adjustable light deviating means, rotatable synchronously with the rotor for bringing the images into coincidence and for controliing the relative movement of the images during rotation of the rotor and scale means for indicating the adjustment of the light deviating means when the images are in coincidenoe and said relative movement is reduced to zero.

3. A binocular range finder comprising two combination coincident-type and moving viewpoint range finders each according to claim 2, the two eyepieces being at interocular separation and also comprising stereoscopic graticules stereoscopically positioned in the two focus planes.

4. A range finder comprising a support, an eyepiece carried by the support, a rotor rotatably mounted on the front of the support, two reflectors carried approximately parallel to one another by the rotor and at an acute angle to the axis of rotation of the rotor, one reflector being in alignment with the axis and having a central aperture for admitting light from the object whose range is to be found, the other reflector being near the rim of the rotor for receiving light from the object and for reflecting it to the axis reflector, means for forming in the focus plane of the eyepiece two superposed images of the object, one by light through the central aperture and the other by light reflected by the reflectors, adjustable means coupled to rotate With the rotor for controlling the amount of relative movement of the images while the rotor rotates and scale means for indicating the adjustment of the control means when said relative movement is reduced to zero.

' 5. A range finder according to claim 4 in which the central aperture receives light directly from the object and said control means acts only on the light reflected by the reflectors.

6. A range finder according to claim 4 in which two additional approximately parallel reflectors are carried by the rotor at an acute angle to the axis, one in front of the central aperture and the other near the rim of the rotor diametrically opposite the first-mentioned rim reflector and said control means act equally and oppositely on the light through the central aperture and the light reflected by the reflectors defined in claim 4.

BENJAMIN E. LUIBOSHEZ. 

